Not least because it's really weird that May wants to see foreigners get a decent minimum annual salary but not British workers, who must make do with £6.70 per hour, or £14,000 a year, assuming 52 40-hour weeks.

So what is the best strategy for the UK to make itself even richer — or weather the storm — depending on how you see the next few years unfolding?

In both scenarios, the strategy is the same, economists of both left and right agree: You want to improve "labour productivity," which is the fancy academic term that refers to creating jobs that are higher paid and produce higher profits. A computer science researcher is more productive than a bartender because the engineer earns more money. And the software the engineer makes creates more profits, compared to pulling pints in a pub. To put it in real terms, the UK needs to be a nation of software coders rather than a nation of bartenders (even if the latter sounds like it might be more fun).

Mark Knickrehm, group CEO of Accenture Strategy, agrees. He told Business Insider, "31% of the UK economy can be attributed to some form of digital skills, capital or intermediate goods flowing through supply chains ... There is not so much evidence of a drain of talent as a continuous struggle to attract the right digital skills."

Facebook might be an American company, but it employs about 400 people in London at an average salary of £210,000 a year. These are the jobs we want. Yet May wants to put up a financial barrier, and a bunch of paperwork, to make it harder. (Yes, the £1,000 levy is peanuts compared to tech salaries, but many small startups don't have the admin staff, the HR people, the lawyers, or the time and energy to jump through the Home Office's hoops. Those are the people who will be hit hardest in this plan.)

David Cameron, making it harder for tech workers to get from A to B. Paul Rogers - WPA Pool/Getty Images May's plan is a response to Prime Minister David Cameron's promise to reduce immigration generally, on the theory that British companies will be forced to employ British people instead. The levy will fund a British worker training program. This theory is turning out to be useless given that the UK is now technically at full employment, and has been for months. We have run out of British people to employ — they all have jobs already.

The issue of whether workers ought to have the right to travel freely, and offer their labour wherever they want, is one of those rare economic principles on which both right and left are in full agreement. No one on the left thinks workers should be restricted from travelling to another country to work. The capitalists agree: Barclays' chief European economist Philippe Gudin published a report noting that the migration of 1 million refugees into Germany over the last year is likely to boost the economy there. That is largely due to two factors, Gudin says. First, 86% of Syrian refugees have secondary or higher education degrees. Second, they are so poor they will spend 80% of the welfare benefits they receive. The multiplier effect from all that smart new labour, coupled with the new spending, "adds 0.6% to private consumption growth in 2016 and 0.36% in 2017," Gudin estimates:

Barclays

This notion — that immigration generally adds to economic growth — is not controversial among economists. That's the way the economy works: the work of new workers adds value and demand, and then growth. If you shut the doors to new workers, you end up like Japan, whose decrepit economy has limped through three decades of near-zero growth precisely because its population is getting older, isn't growing, and the Japanese have a deep-seated, long-standing dislike of immigration:

If you want to keep that going — if you want workers to earn more, and for their work to produce more value and more economic growth — then the easiest way is to let in the smartest workers from elsewhere, and let them work.

If we were being economically rational, we might consider paying high-skilled workers to move here, or giving tech companies tax breaks to add skilled foreigners.

Apple founder Steve Jobs was the son of Syrian immigrants. Google founder Sergey Brin was born in Russia. We don't know where the next Jobs or Brin is coming from, but we can guarantee that a £1,000 annual tax on being clever is more likely to make them skip Britain and go elsewhere.